Rockwell Automation 20-COMM-H RS485 HVAC Adapter FRN 2.xxx - Manual (Page 49)

Using Metasys N2 5-3
20-COMM-H RS-485 HVAC Adapter User Manual
Publication 20COMM-UM009D-EN-P
Using the Metasys N2 Point
Map for I/O On Metasys N2, data transfers are used to transfer the I/O data that controls
the drive and sets its Reference. Note that Output I/O is data that the master
device sends and the adapter receives. Input I/O is status data that the
adapter sends and the master device receives.
Important: In order for the drive to use the I/O and Reference from the
Metasys N2 network, you must set parameters in it and the
adapter to receive the I/O and Reference. For details, refer to
Setting the I/O Configuration on page 3-5 .
Setting the Logic Command and Reference
On Metasys N2, there are two ways to set the logic command: binary
outputs (
Table 5.L on page 5-5 ) and an analog output ( Table 5.M on
page 5-6 ).
•
When you need to set only one bit in the Logic Command word, you can
use binary outputs. For example, to stop a PowerFlex 70/700 drive (bit
0), you can use a binary output (BO#1).
•
When you need to set multi-bit fields in the Logic Command word or to
set the entire Logic Command word, you must use the analog output to
maintain data integrity. For example, to set the Reference Selection of a
PowerFlex 70/700 drive (bits 12…14), you must use an analog output
(AO#1).
A 16-bit product logic word is buffered in the adapter, holding the last Logic
Command sent to the drive regardless of whether it was sent through the
binary outputs or through product logic command outputs (AO#1). When a
bit is updated through either of these outputs, a new Logic Command will
be generated and sent to the drive.
To set the Reference, you must use an analog output (AO#2). Table 5.G
shows example References and their results on a PowerFlex 70/700 drive
that has its Parameters 55 - [Maximum Freq] set to 70 Hz and 82 -
[Maximum Speed] set to 60 Hz, and adapter Parameter 29 - [N2 Ref
Scale] is set to 32,767.
!
ATTENTION: Select and use either the point type Digital (BO)
or the word type Analog (AO) as a control method, but not both.
Conflicts caused from using both methods can result in dangerous
operation. Failure to observe this precaution could cause bodily
injury and/or damage to equipment.